/**
 * Software License, Version 1.0
 * 
 * Copyright 2003 The Trustees of Indiana University.  All rights reserved.
 * 
 *
 *Redistribution and use in source and binary forms, with or without 
 *modification, are permitted provided that the following conditions are met:
 *
 *1) All redistributions of source code must retain the above copyright notice,
 * the list of authors in the original source code, this list of conditions and
 * the disclaimer listed in this license;
 *2) All redistributions in binary form must reproduce the above copyright 
 * notice, this list of conditions and the disclaimer listed in this license in
 * the documentation and/or other materials provided with the distribution;
 *3) Any documentation included with all redistributions must include the 
 * following acknowledgement:
 *
 *"This product includes software developed by the Community Grids Lab. For 
 * further information contact the Community Grids Lab at 
 * http://communitygrids.iu.edu/."
 *
 * Alternatively, this acknowledgement may appear in the software itself, and 
 * wherever such third-party acknowledgments normally appear.
 * 
 *4) The name Indiana University or Community Grids Lab or NaradaBrokering, 
 * shall not be used to endorse or promote products derived from this software 
 * without prior written permission from Indiana University.  For written 
 * permission, please contact the Advanced Research and Technology Institute 
 * ("ARTI") at 351 West 10th Street, Indianapolis, Indiana 46202.
 *5) Products derived from this software may not be called NaradaBrokering, 
 * nor may Indiana University or Community Grids Lab or NaradaBrokering appear
 * in their name, without prior written permission of ARTI.
 * 
 *
 * Indiana University provides no reassurances that the source code provided 
 * does not infringe the patent or any other intellectual property rights of 
 * any other entity.  Indiana University disclaims any liability to any 
 * recipient for claims brought by any other entity based on infringement of 
 * intellectual property rights or otherwise.  
 *
 *LICENSEE UNDERSTANDS THAT SOFTWARE IS PROVIDED "AS IS" FOR WHICH NO 
 *WARRANTIES AS TO CAPABILITIES OR ACCURACY ARE MADE. INDIANA UNIVERSITY GIVES
 *NO WARRANTIES AND MAKES NO REPRESENTATION THAT SOFTWARE IS FREE OF 
 *INFRINGEMENT OF THIRD PARTY PATENT, COPYRIGHT, OR OTHER PROPRIETARY RIGHTS. 
 *INDIANA UNIVERSITY MAKES NO WARRANTIES THAT SOFTWARE IS FREE FROM "BUGS", 
 *"VIRUSES", "TROJAN HORSES", "TRAP DOORS", "WORMS", OR OTHER HARMFUL CODE.  
 *LICENSEE ASSUMES THE ENTIRE RISK AS TO THE PERFORMANCE OF SOFTWARE AND/OR 
 *ASSOCIATED MATERIALS, AND TO THE PERFORMANCE AND VALIDITY OF INFORMATION 
 *GENERATED USING SOFTWARE.
 */
package cgl.narada.wsinfra.wse.matching;

import java.util.Enumeration;
import java.util.Vector;

import org.apache.xmlbeans.XmlCursor;

import cgl.narada.wsinfra.exception.ProcessingException;
import cgl.narada.wsinfra.schemas.eventing.FilterType;
import cgl.narada.wsinfra.schemas.soap.EnvelopeDocument;
import cgl.narada.wsinfra.wse.matching.capability.CapabilityRegistration;

/**
    This is the matching engine for the system.

    @author Shrideep Pallickara
    $Date: 2005/07/29 22:41:30 $
    $Revision: 1.6 $
*/


public class MatchingEngine {

  private SubscriptionManagement subscriptionManagement;
  private MatchingCapabilityFactory matchingCapabilityFactory;
  private String moduleName = "MatchingEngine: ";

  public MatchingEngine(SubscriptionManagement subscriptionManagement) {
    this.subscriptionManagement = subscriptionManagement;
    matchingCapabilityFactory = MatchingCapabilityFactory.getInstance();
    CapabilityRegistration.getInstance().registerCapabilities();
  }


  /** Computes the list of destinations that an event should be routed to. */
  public Vector
  performMatching(EnvelopeDocument envelopeDocument,
		  boolean suppressDuplicates)  
    throws ProcessingException {
    if (envelopeDocument == null) {
      return null;
    }

    return processSubscriptions(envelopeDocument, suppressDuplicates);
  }


  /** Processes subscriptions contained in SubscriptionManagement, and computes
      destinations associated with the supplied document. */
  private Vector processSubscriptions(EnvelopeDocument envelopeDocument,
				      boolean suppressDuplicates)  
    throws ProcessingException {
    Vector disseminationVector = new Vector();
    Enumeration identifiers =
      subscriptionManagement.getSubscriptionIdentifiers();

    while (identifiers.hasMoreElements()) {
      String identifier = (String) identifiers.nextElement();
      SubscriptionEntry subEntry = subscriptionManagement.getEntry(identifier);

      if (subEntry == null) {
	continue;
      }

      XmlCursor filterCursor = subEntry.getFilter().newCursor();
      String constraint = filterCursor.getTextValue();
      filterCursor.dispose();
      String report = moduleName + "Processing subscription [" + identifier +
	"] dialect=" + subEntry.getFilter().getDialect() + ", constraint=" +
	constraint;


      System.out.println(report);
      
      if (!suppressDuplicates) {
	boolean match = processSubscription(envelopeDocument, subEntry);
      } else {
	boolean performMatching = shouldPerformMatching(disseminationVector,
							subEntry);
	if (performMatching) {
	  boolean match = processSubscription(envelopeDocument, subEntry);
	  if (match) {
	    disseminationVector.addElement(subEntry.getSink());
	  }
	}// end if (performMatching)

      } // end if (suppressDuplicates)

    } // end while(hasMoreElements())

    return disseminationVector;
  }


  /** Checks to see if Matching indeed needs to be performed. This comes into
      play in scenarios where a suppressDuplicates has been provided */
  private boolean shouldPerformMatching(Vector disseminationVector,
					SubscriptionEntry subscriptionEntry) {
    if (subscriptionEntry == null) {
      return false;
    }

    if (disseminationVector.contains(subscriptionEntry.getSink())) {
      return false;
    }

    return true;
  }



  /** This method matches an envelopeDocument to the subscriptionEntry
      supplied as the other parameter. */
  private boolean 
  processSubscription(EnvelopeDocument envelopeDocument,
		      SubscriptionEntry subscriptionEntry) 
  throws ProcessingException {
    String errorReport = null;
    if (envelopeDocument == null) {
      errorReport = moduleName + "Specified envelope is NULL";
      throw new ProcessingException(errorReport);
    }

    if (subscriptionEntry == null) {
      errorReport = moduleName + "Specified SubscriptionEntry is NULL";
      throw new ProcessingException(errorReport);
    }

    String identifier = subscriptionEntry.getIdentifier();
    FilterType filter = subscriptionEntry.getFilter();
    if (filter == null) {
      errorReport = moduleName + "The Filter corresponding to [" +
	identifier + "] is NULL! This should not have been the case";
      throw new ProcessingException(errorReport);
    }

    String dialect = filter.getDialect();
    if (dialect == null) {
      errorReport = moduleName + "The Dialect corresponding to [" +
	identifier + "] is NULL! This should not have been the case";
      throw new ProcessingException(errorReport);
    }

    MatchingCapability matchingCapability =
      matchingCapabilityFactory.getCapability(dialect);
    
    if (matchingCapability == null) {
      errorReport = moduleName +  "Matching Capability for dialect [" +
	dialect + "] is NOT currently registered!";
      throw new ProcessingException(errorReport);
    }

    boolean matchResult =
      matchingCapability.performMatching(envelopeDocument, filter);

    if (matchResult) {
      System.out.println(moduleName + "A match is found!");
    }

    return matchResult;
  }



}
